Marvel's star-studded sequel to its 2012 ensemble film is expected to launch to $210 million or better for the weekend, setting a new threshold for how high a film can open (one tracking service even has it at $224 million).

See what top critics are saying about Avengers: Age of Ultron:

The Hollywood Reporter'sTodd McCarthy notes, "The powers of Marvel's all-star superheroes go a bit wobbly ... [as] Whedon mixes some brooding down time in with the abundant spectacle. To be sure, series junkies will get their fix from the sheer massiveness of the exploits, but at least two of the big action scenes are lackluster, while the climax and resolution could have been worked out in more complex, less rote ways, so as to further increase intrigue and anticipation for Avengers: Infinity War parts one and two. ... [It] at moments takes a peek down some shadowy side roads but ends up mostly zooming along the main highway to deliver what the audience wants rather than something even a little bit different."

"Ultimately, Whedon's efforts to invest the heroes with a degree of unsurety and vulnerability comes off as half-baked, as such an effort can only go so far due to the nature of the material. After all, these are comic book characters defined by their double identities; a third dimension is neither required nor perhaps even desired. ... [It] succeeds in the top priority of introducing a worthy opponent for its superheroes and giving the latter a few new things to do, but this time the action scenes don't always measure up and some of the characters are left in a kind of dramatic no man's land. The returning series actors acquit themselves in the expected agreeable manner, while series newcomer Serkis has a terrific couple of minutes as a tough but stressed South African criminal." Plus, Ultron is "voiced with marvelous robotic nuance by Spader" and "a very welcome addition to the team comes in the form of the android Vision," played by Bettany.

The New York Times'Manohla Dargis says it "isn't half-bad" and is "outlandishly overpacked," but "the most relevant thing about a movie like this is that its quality is almost entirely irrelevant. It was created to crush the box office, entertainment media and audience resistance, and mission, you know, already accomplished. ... Whedon chews over the same in Age of Ultron (war and people, what are they good for?) in his efforts to personalize the material while dutifully hitting all the genre notes. This Avengers doesn’t always pop the way that the first one sometimes did, partly because its villain isn’t as memorable, despite Spader’s silky threat. And, as is often the case in these comic book movies, most of the fights are interminable and fatiguing, though Whedon does fold in moments of beauty, including when the image slows down with each Avenger centered in the frame both together and individually."

Still, Whedon's "characters banter and quip like screwball loons while parading their cultural literacy (here, someone name-drops Eugene O’Neill), but these are linguistic fig leaves for men and women who feel and hurt deeply," and "Ruffalo lifts his every scene, as does Johansson, even if she doesn’t have much to do but strut in her form-fitting costume and exchange meaningful looks with a romantic foil. ... Repeatedly, Whedon injects something alive into the mix, be it a woman’s fingers tenderly caressing a computer-generated wrist or children leaping into a father’s embrace. This assertion of flesh-and-blood vulnerability extends to several narrative points, including a nod at the military industrial complex that is almost touchingly pointless given how much of this movie has been dedicated to ensuring obliterating violence looks cool."

Los Angeles Times'Kenneth Turan explains, "Even as all these good things are acknowledged, the uncomfortable reality remains that although this movie is effective moment to moment, very little of it lingers in the mind afterward." Despite clever dialogue, new characters and amped-up romance, "where this Avengers movie is at its weakest is in its plot. Well-made though each action sequence may be, there are so many of them, including more going on in the pre-credits sequence than in many entire films, that everything blurs together. ... Whether this is what fans ravenous for nonstop stimulation want, what Whedon prefers or what the Marvel hierarchy mandates, all this action overloads the senses. When you add in a bloated running time of 2 hours, 22 minutes, what happens on the screen stays on the screen and is difficult to recall later on. That's a shame, because it detracts from Ultron, one of the most memorable Marvel movie villains and an entity impossible to confuse with anything else."

The Washington Post'sAnn Hornaday praises, "As he did in the first Avengers, Whedon avoids the fatal trap of comic book ­self-seriousness, leavening a baggy, busy, overpopulated story with zippy one-liners, quippy asides and an overarching tone of jaunty good fun. Whedon never lets the dark stuff overwhelm the easygoing, even warm, atmosphere he’s set up. ... Casting has been a crucial element in the Avengers formula, and once again Whedon has enlisted surpassingly gifted actors to inhabit an ever-widening shared universe. He’s wise enough to know that these funny, conflicted, deeply pained characters are never more human than when they’re at their most monstrous."

USA Today'sClaudia Puig gives it two-and-a-half stars out of four. "Cutting Whedon some slack, it's an all-star superhero saga that will likely please diehard Marvel devotees and many fans of the first film. But for the less dialed in, the fun of watching these top-tier heroes save the universe diminishes with the passage of time." Still, "Whedon's strong suits are snarky, fast-paced humor and charismatic characters, and those two elements give Ultron its greatest appeal. ... Although the plot has moments of murkiness, the spectacle is substantial and the witty company delightful. If only the editing had been tighter."